Electric Transmission Line Ground Fault Prevention Systems Using Dual Parameter Monitoring with High Sensitivity Relay Devices in Parallel with Low Sensitivity Relay Devices

ABSTRACT

A system for preventing ground fault in a three-phase electric transmission line system caused by a line break, includes: the transmission lines, a programmable relay protection system, including a plurality of existing low sensitivity (LS) relays and a corresponding set of high sensitivity (HS) relays in parallel with the is relays. The HS relays on each line are programmed to include: preset acceptable operating parameter ranges of at least two electric operating conditions, at least one high sensitivity instantaneous undercurrent and at least one high sensitivity condition selected from line differential overcurrent and negative sequence overcurrent (and combinations thereof); monitoring; permitting closed circuit operation when all of the lines show that the two operating conditions are within the preset acceptable operating parameter ranges; tripping a circuit breaker on a broken line when that line shows that the two operating conditions are outside the preset parameter ranges; and shutting down power to the broken line before it otherwise causes a ground fault or other short circuit.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. Utilitypatent application Ser. No. 17/672,422, titled “Electric TransmissionLine Ground Fault Prevention Methods Using Dual, High SensitivityMonitoring”, filed on 15 Feb. 2022, by the same inventors herein and isalso a continuation-in-part of co-pending U.S. Utility patentapplication Ser. No. 17/693,504, titled “Electric Transmission LineGround Fault Prevention Systems Using Dual, High Sensitivity MonitoringDevices”, filed on Mar. 14, 2022, by the same inventors herein.

BACKGROUND OF INVENTION a. Field of Invention

High voltage (sometimes referred to as high tension) and other threephase electric transmission systems are prone to failing lines thatcause ground faults or other short circuits. Typically, such failuresresult from breaks in an individual line, connection breaks, objectintersection, aging, adverse weather, support structure failure, etc.For example, transmission lines that were built decades ago have aged tothe point where conductors (lines) separate from splices, or otherwisebreak and open with double jumpers and double dead end (DDE) towers.These double jumpers may slap against the steel towers or otherwiseground to cause fires and/or injury to structures, persons, animals andwildlife and flora. In the case of two major 2018 California fires, manyhomes and entire towns were destroyed by fire caused by ground faultsresulting from broken lines.

Historically, the industry has focused attention to preservation oftransmission lines, transformers, generators and substations bymonitoring systems for shorts and ground faults, reacting according tothe concept of best methods for preserving equipment and maintainingbest (least interrupted) services to the load (consumers). Thus, fordecades and presently, the industry utilizes preprogrammed relays thatmonitor operating conditions to identify shorts and to shut downelectricity on the shorted line and isolate to provide electricity tothe consumer. These relays react once a ground fault or other short hasoccurred. These prior art relays have a sensitivity of about 1 amp orlower, generally being about 0.5 amps sensitivity, and not as low as 0.1amps sensitivity. These “low sensitivity” relays are incapable ofsensing, much less monitoring, parameters that operate (flow) at loweramps than these low sensitivity limited relays. The present invention isdirected to a very different approach—the use of methods, devices andsystems that focus on identifying a break in a line before a short orground fault occurs, thereby preventing disasters that may result fromsuch shorts and ground faults. There are about 1.3 to 1.7 secondsbetween the time a line breaks and the time a short occurs (i.e., thetime it takes to touch a foreign conductor, such as ground, tower orbuilding). The present invention is directed to unique systems anddevices to see the break in real time within fractions of a second, evenmilliseconds, and to likewise shut down the line (trip the breaker(s))within fractions of a second and, hence, before any short occurs, avoidmany possible disasters. This is achieved by micro-monitoring, lookingat different parameters (operating conditions) from those used in theprior art relays, and reacting nearly instantaneously. Specifically, inthe field where low sensitivity relays are already in place, oneimportant aspect of the present invention is to place high sensitivityrelays in parallel to the already in place low sensitivity relays, andto use these high sensitivity relays to monitor very low flow rateparameter functions to prevent ground fault disasters. “Highsensitivity” relays as used herein means relays that can measure/monitorparameters at 0.1 amps or lower, such as 0.05 amps or lower. Preferredare high sensitivity relays that can operate as low as 0.01 amps andmost preferred are relays that can operate at or below 0.001 amps.

b. Description of Related Art

The following patents are representative of the field pertaining to thepresent invention:

U.S. Pat. No. 6,518,767 to Roberts et al. describes a power line currentdifferential protection system. All three phase current values (I.sub.A, I.sub. B and I.sub. C) are obtained from both the local end and theremote end of a power transmission line. The magnitude of the ratio ofthe remote current values to the local current values are calculated.Also, the angle difference between the local and the remote currentvalues for each phase are calculated. Comparison elements then comparethe ratio and angle values against preselected values which establish arestrain region in the current ratio plane. Current values which resultin the ratio being within the region do not result in a tripping signalfor the circuit breaker on the power transmission line, while currentvalues which result in a ratio outside of the region result in atripping of the circuit breaker. Similar circuitry is used for negativesequence current quantities, with the negative sequence preselectedvalues being set substantially lower to produce a more sensitiveresponse to possible faults in the line.

U.S. Pat. No. 10,197,614 to Benmouyal et al. illustrates the errors thatare encountered when using both single-ended and double-endednormal-mode fault location calculations when a fault occurs in apole-open condition. The disclosure provides systems and methods foraccurately calculating the location of faults that occur duringpole-open conditions, including single-ended approaches and double-endedapproaches.

U.S. Pat. No. 10,340,684 to Sridharan et al. describes how a location ofa broken electrical conductor of an electric power delivery system maybe detected by monitoring a rate of change of phase voltage and/or arate of change of zero-sequence voltage at various points on theconductor. Intelligent electronic devices (IEDs) such as phasormeasurement units may be used to obtain measurements and calculatesynchrophasors. The synchrophasors may be used by a central controllerto determine which two continuous IEDs measure rates of change ofvoltages of opposite polarities, where the broken conductor is betweenthe two continuous IEDs. The synchrophasors may be used by a centralcontroller to determine which two continuous IEDs where one exhibits azero-sequence voltage magnitude that exceeds a predetermined thresholdfor a predetermined time, wherein the zero-sequence voltage magnitude ofthe other of the continuous IEDs does not exceed the predeterminedthreshold.

U.S. Pat. No. 10,823,777 to Dase et al. relates to detecting a brokenconductor in a power transmission line. In an embodiment, a processorreceives a signal indicating current on the transmission line. Theprocessor determines that a broken conductor is present on thetransmission line based at least in part on a magnitude of the currentbeing less than a line charging current of the transmission line and aphase angle of the current leading a respective phase voltage of thetransmission line. The processor effects a control operation based onthe determined broken conductor.

U.S. Pat. No. 10,955,455 to Thompson et al. pertains to detection of abroken conductor in an electric power system. In one embodiment, abroken conductor detector may be configured to be mounted to anelectrical conductor and may comprise a communication subsystemconfigured to transmit a signal configured to indicate that theconductor is broken. A sensor may determine an operating vector. Aprocessing subsystem may be configured to receive the operating vectorfrom the sensor and to identify when the operating vector is outside ofa range defined by a rest vector and a threshold value. In certainembodiments, the threshold may comprise a three-dimensional sphere. Theprocessing subsystem may determine that the conductor is broken based onthe operating vector remaining outside of the range for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is broken.

U.S. Pat. No. 11,211,788 to Wade et al. describes how systems andmethods may mitigate risk of fire caused by an electric power system. Inone embodiment, a system may include an intelligent electronic device(IED). The IED includes a communication subsystem to receive a signalfrom a sensor related to a condition of the electric conductor. Aprocessing subsystem in communication with the communication subsystemmay operate in at least two modes comprising a high security mode and afire prevention mode. In the fire prevention mode, the IED may interrupta flow of electric current based on the signal from the at least onesensor associated with the electric conductor. In the high securitymode, the system may interrupt a flow of electric current based on thesignal from the at least one sensor associated with the electricconductor and based on a second condition relating to the electricconductor.

US Publication No. 20190317143 to Gangadhar et al. relates to detectinga broken conductor in a power transmission line. In an embodiment, aprocessor receives a signal indicating current on the transmission line.The processor determines that a broken conductor is present on thetransmission line based at least in part on a magnitude of the currentbeing less than a line charging current of the transmission line and aphase angle of the current leading a respective phase voltage of thetransmission line. The processor effects a control operation based onthe determined broken conductor.

US Publication No. 20190324074 to Thompson et al. pertains to detectionof a broken conductor in an electric power system. In one embodiment, abroken conductor detector may be configured to be mounted to anelectrical conductor and may comprise a communication subsystemconfigured to transmit a signal configured to indicate that theconductor is broken. A sensor may determine an operating vector. Aprocessing subsystem may be configured to receive the operating vectorfrom the sensor and to identify when the operating vector is outside ofa range defined by a rest vector and a threshold value. In certainembodiments, the threshold may comprise a three-dimensional sphere. Theprocessing subsystem may determine that the conductor is broken based onthe operating vector remaining outside of the range for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is broken.

US Publication No. 20210048486 to Bell et al. describes systems fordetermining a broken conductor condition in a multiple-phase electricpower delivery system. It has been observed that broken conductors posea safety concern when occurring in the presence of people or vulnerableenvironmental conditions. Broken conductor conditions disclosed hereinmay be used to detect and trip the phase with the broken conductor, thusreducing or even eliminating the safety risk. Further, a distance to theopening may be determined.

US Publication No. 20210091559 to Mobley et al. pertains to detection ofa broken conductor in an electric power system. In one embodiment, abroken conductor detector may be configured to be mounted to anelectrical conductor and may comprise a communication subsystemconfigured to transmit a signal configured to indicate that theconductor is broken. A sensor may determine a plurality of vectors. Aprocessing subsystem may be configured to receive the plurality ofvectors from the sensor and to identify when the vector is outside of arange defined by a threshold value. The processing subsystem maydetermine that the conductor is falling based on the plurality ofvectors remaining outside of the threshold for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is falling.

US Publication No. 20210265834 to Wade et al. describes how systems andmethods may mitigate risk of fire caused by an electric power system. Inone embodiment, a system may include an intelligent electronic device(IED). The IED includes a communication subsystem to receive a signalfrom a sensor related to a condition of the electric conductor. Aprocessing subsystem in communication with the communication subsystemmay operate in at least two modes comprising a high security mode and afire prevention mode. In the fire prevention mode, the IED may interrupta flow of electric current based on the signal from the at least onesensor associated with the electric conductor. In the high securitymode, the system may interrupt a flow of electric current based on thesignal from the at least one sensor associated with the electricconductor and based on a second condition relating to the electricconductor.

Published article 2016 IEEE “Catching Falling Conductors inMidair—Detecting and Tripping Broken Distribution Circuit Conductors atProtection Speeds” by William O'Brien, Eric Udren, Kamal Garg, DennisHaes, and Bala Sridharan describes how when an overhead electric powerdistribution circuit conductor breaks—for example, when a car strikes apole or a splice or clamp fails—the energized conductor falls to ground.The resulting high-impedance ground fault may be difficult or impossibleto detect by relays located in the substation. In any case, no groundfault protection relay can operate until well after the time the faulthas occurred—after the falling energized conductor has hit the groundand created a hazardous situation. For decades, utilities and equipmentmanufacturers have worked to develop methods for tripping thesehazardous ground faults as quickly as possible. This paper describes anew falling conductor detection scheme that trips the affected circuitsection in the narrow time window between the moment of the break andthe time the conductor hits the ground. The affected circuit section isde-energized while the conductor is still falling, eliminating the riskof an arcing ground fault or energized circuits on the ground.

Published article 2019 Schweitzer Engineering Laboratories, Inc.“Detecting and Locating Broken Conductor Faults on High-Voltage Lines toPrevent Autoreclosing Onto Permanent Faults” by Kanchanrao Dase, SajalHarmukh, and Arunabha Chatterjee describes how broken-conductordetection is challenging because the conductor may remain suspendedwithout causing any fault current. Even if the conductor falls to theground, the fault current might remain low, depending on the faultresistance. For low-resistance faults, a relay can detect faults andtrip the line breakers. However, because the relay cannot determinewhether the fault is permanent, it may attempt to reclose, causingfurther stress to the power system. This paper describes a new algorithmthat uses only single-ended measurements to reliably detect brokenconductors and estimate their location by using the charging current ofthe line. The phase angle of this current leads the voltage by aboutL90°, and the magnitude is a function of line length. This method issuitable for power lines that have measurable charging current, and itdetects broken conductors successfully if the relay can measure thecharging current while the conductor is falling in midair.Broken-conductor detection can be used to trip the breakers before theconductor touches the ground and creates a shunt fault. Thus, thealgorithm can prevent such faults and block any attempt to reclose theline. Detecting broken conductors and their location informationprovided by the algorithm can help in quickly resolving broken-conductorfaults. This paper presents three field events from 57.1 kV and 220 kVlines and results from Electromagnetic Transients Program (EMTP)simulations that validate the algorithm.

U.S. Pat. No. 9,753,096 to Kim and related U.S. Pat. No. 8,866,626 toKim both describe a method, system and computer software for detectingan incipient failure of a generator in a power system including thesteps of ascertaining one or more generator reference parameter of thegenerator for use as a baseline reference; measuring one or moreoperating parameter values of the generator; using the one or moreoperating parameter values to solve for an estimated present value ofthe one or more of the generator's current performance parameters usingparticle swarm optimization technique; and determining whether theestimated present values of the one or more of the generator's currentperformance parameters are outside of an acceptable limit.

U.S. Pat. No. 7,345,456 to Gibbs et al. describes a stabilizer andsynchronous electric power generator system using same that providesboth power system damping and excitation limiter functionality. Thestabilizer includes a processing unit and a memory storing routinesexecutable by the processing unit. The routines are adapted to receive avoltage signal indicative of a voltage and a current signal indicativeof a current output by the generator system, generate, utilizing thevoltage and current signals, a power system stabilizer signal fordamping oscillations and one or more excitation limiter function signalsfor controlling excitation level. The routines are also adapted togenerate a feedback signal for the generator system by combining thepower system stabilizer signal and one or more of the one or moreexcitation limiter function signals.

U.S. Pat. No. 5,761,073 to Dickson describes a programmableautosynchronizer for use with a system having generator and bus voltagesand having a breaker circuit for connecting the generator and busvoltages to each other. The autosynchronizer synchronizes the frequencyand phase of the generator and bus AC voltages by controlling thegenerator voltage. A microprocessor compares the frequencies ofgenerator and bus voltage signals, the microprocessor generating aproportional difference signal having a parameter representative of aproportional difference in frequency between the generator and busvoltage signals. The permits a sync signal when the frequency differenceof the frequencies of the generator and bus voltage signals is withinthe synchronization frequency range. A first output circuit responsiveto the proportional difference signal provides a correction signal tothe generator for varying the frequency of the generator. A secondoutput circuit responsive to the sync signal provides a breaker closesignal to the breaker circuit for closing the breaker thereby enablingconnection of the generator and bus voltages. A frequency correctiondead band within the frequency range and a target slip band within thedead band define a zone of limited proportional correction to nudge thegenerator into synchronization and prevent a hung scope.

U.S. Pat. No. 5,751,532 to Kanuchok, et al. describes a relay formonitoring an electrical system to protect the electrical system from anovercurrent condition as a time dependent function of an electricalcurrent level in the electrical system is disclosed. The relay includesa memory which stores a current level count and a current level detectorcoupled to the electrical system which detects the electrical currentlevel in the electrical system over time. A microprocessor responds tothe current level detector by varying the current level count in thememory as a function of the electrical current level over time. Themicroprocessor also detects an occurrence of the electrical currentlevel falling below a minimum current level. A timer responds to themicroprocessor by measuring a period of time during which the electricalcurrent level is less than the minimum current level. The microprocessorresponds to the timer by varying the current level count in the memoryas a function of the measured period of time during which the electricalcurrent level is below the minimum current level. A method of monitoringan electrical system to protect the electrical system from anovercurrent condition as a time dependent function of an electricalcurrent level in the electrical system is also disclosed. Otherapparatus and methods are also disclosed.

U.S. Pat. No. 5,640,060 to Dickson describes an autosynchronizer for usewith a system having generator and bus voltages and having a breakercircuit for connecting the generator and bus voltages to each other. Theautosynchronizer synchronizes the frequency and phase of the generatorand bus AC voltages by controlling the generator voltage. Amicroprocessor compares the frequencies of generator and bus voltagesignals, the microprocessor generating a proportional difference signalhaving a parameter representative of a proportional difference infrequency between the generator and bus voltage signals. The permits async signal when the frequency difference of the frequencies of thegenerator and bus voltage signals is within the synchronizationfrequency range. A first output circuit responsive to the proportionaldifference signal provides a correction signal to the generator forvarying the frequency of the generator. A second output circuitresponsive to the sync signal provides a breaker close signal to thebreaker circuit for closing the breaker thereby enabling connection ofthe generator and bus voltages. A frequency correction dead band withinthe frequency range and a target slip band within the dead band define azone of limited proportional correction to nudge the generator intosynchronization and prevent a hung scope.

U.S. Pat. No. 5,309,312 to Wilkerson, et al. describes an apparatus forprotecting an electrical power system supplying electrical power to anelectrical load comprises a transformer for sensing an operatingcondition of the electrical power system and for producing an analogsignal representative of the operating condition, and a microcomputerfor periodically sampling the analog signal and for converting theanalog signal into a series of digital signals. The microcomputerincludes circuitry for deriving a digital value representative of asquare root of the series of digital signals and circuitry forprocessing the digital value over time to determine a processed valuewhich is a function of both the sensed operating condition and time. Acircuit breaker is responsive to the microcomputer for disconnecting thepower system from the load in the event that the processed value is notwithin preset limits. The microcomputer also generates a relay signalrepresentative of the status of the relay and the relay includes anoutput port responsive to the relay signal, for communicating the statusof the relay to a remote station.

U.S. Pat. No. 5,014,153 to Wilkerson describes an apparatus formonitoring phased currents in a first winding and a second winding of atransformer and for disconnecting the transformer from a power sourcesupplying the transformer when a difference between the magnitude of thecurrent in the first winding and the magnitude of the current in thesecond winding exceeds a predetermined amount to indicate a faultcondition is disclosed. The apparatus is used in combination withcircuitry for generating first and second current signals each having aphase and magnitude which is a function of the phase and magnitude ofthe phased currents in the first and second windings, respectively. Theapparatus includes a circuit for shifting the phase of the secondcurrent signal to match the phase of the first current signal, a circuitfor detecting a difference between the magnitude of the first currentsignal and the magnitude of the phase shifted second current signal, anda circuit for disconnecting the transformer from the power source whenthe detected difference exceeds the predetermined amount.

U.S. Pat. No. 4,788,619 to Ott, et al. describes a protective relay foruse in an electrical power system having electrical conductors which areenergized with an AC voltage. The protective relay includes a circuitfor sensing the AC voltage to produce an AC output that has zerocrossings and a time period between zero crossings, a circuit forsupplying an electrical signal representing a preselected pickup valueof volts-per-Hertz for the relay, and a circuit responsive to the ACoutput and to the electrical signal for generating an electrical levelas a function of both the time period and the pickup value and forproducing an output signal for the relay when the AC output exceeds theelectrical level. In this way, the output signal is produced when avolts-per-Hertz value of the AC voltage exceeds the preselected pickupvalue of volts-per-Hertz for the relay. Other protective relay apparatusand methods are also disclosed.

U.S. Pat. No. 4,757,416 to Wilkerson describes a protective apparatusfor use in an A.C. electrical power system with a circuit breaker forconnecting and disconnecting first and second electrical conductors thatare electrically energized, the conductors normally having a negligiblephase difference of electrical energization when the circuit breaker isclosed, and the circuit breaker having auxiliary contacts defining thestate of the circuit breaker as open or closed. The protective apparatusincludes a circuit responsive to the auxiliary contacts for producing afirst signal representative of the state of the breaker as open orclosed and another circuit connected to the circuit for producing thefirst signal and operable when the breaker is closed for generating asecond signal when the phase difference of electrical energization ofthe first and second electrical conductors exceeds a predeterminedvalue. A further circuit provides an indication of malfunction of thecircuit breaker when the second signal occurs. Phase window extendingapparatus for use in the protective apparatus, methods of operation andother protective apparatus are also disclosed.

U.S. Pat. No. 6,518,767 to Roberts et al. describes a power line currentdifferential protection system. All three phase current values (I.sub.A,I.sub.B and I.sub.C) are obtained from both the local end and the remoteend of a power transmission line. The magnitude of the ratio of theremote current values to the local current values are calculated. Also,the angle difference between the local and the remote current values foreach phase are calculated. Comparison elements then compare the ratioand angle values against preselected values which establish a restrainregion in the current ratio plane. Current values which result in theratio being within the region do not result in a tripping signal for thecircuit breaker on the power transmission line, while current valueswhich result in a ratio outside of the region result in a tripping ofthe circuit breaker. Similar circuitry is used for negative sequencecurrent quantities, with the negative sequence preselected values beingset substantially lower to produce a more sensitive response to possiblefaults in the line.

U.S. Pat. No. 10,197,614 to Benmouyal et al. illustrates the errors thatare encountered when using both single-ended and double-endednormal-mode fault location calculations when a fault occurs in apole-open condition. The disclosure provides systems and methods foraccurately calculating the location of faults that occur duringpole-open conditions, including single-ended approaches and double-endedapproaches.

U.S. Pat. No. 10,340,684 to Sridharan et al. describes how a location ofa broken electrical conductor of an electric power delivery system maybe detected by monitoring a rate of change of phase voltage and/or arate of change of zero-sequence voltage at various points on theconductor. Intelligent electronic devices (IEDs) such as phasormeasurement units may be used to obtain measurements and calculatesynchrophasors. The synchrophasors may be used by a central controllerto determine which two continuous IEDs measure rates of change ofvoltages of opposite polarities, where the broken conductor is betweenthe two continuous IEDs. The synchrophasors may be used by a centralcontroller to determine which two continuous IEDs where one exhibits azero-sequence voltage magnitude that exceeds a predetermined thresholdfor a predetermined time, wherein the zero-sequence voltage magnitude ofthe other of the continuous IEDs does not exceed the predeterminedthreshold.

U.S. Pat. No. 10,823,777 to Dase et al. relates to detecting a brokenconductor in a power transmission line. In an embodiment, a processorreceives a signal indicating current on the transmission line. Theprocessor determines that a broken conductor is present on thetransmission line based at least in part on a magnitude of the currentbeing less than a line charging current of the transmission line and aphase angle of the current leading a respective phase voltage of thetransmission line. The processor effects a control operation based onthe determined broken conductor.

U.S. Pat. No. 10,955,455 to Thompson et al. pertains to detection of abroken conductor in an electric power system. In one embodiment, abroken conductor detector may be configured to be mounted to anelectrical conductor and may comprise a communication subsystemconfigured to transmit a signal configured to indicate that theconductor is broken. A sensor may determine an operating vector. Aprocessing subsystem may be configured to receive the operating vectorfrom the sensor and to identify when the operating vector is outside ofa range defined by a rest vector and a threshold value. In certainembodiments, the threshold may comprise a three-dimensional sphere. Theprocessing subsystem may determine that the conductor is broken based onthe operating vector remaining outside of the range for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is broken.

U.S. Pat. No. 11,211,788 to Wade et al. describes how systems andmethods may mitigate risk of fire caused by an electric power system. Inone embodiment, a system may include an intelligent electronic device(IED). The IED includes a communication subsystem to receive a signalfrom a sensor related to a condition of the electric conductor. Aprocessing subsystem in communication with the communication subsystemmay operate in at least two modes comprising a high security mode and afire prevention mode. In the fire prevention mode, the IED may interrupta flow of electric current based on the signal from the at least onesensor associated with the electric conductor. In the high securitymode, the system may interrupt a flow of electric current based on thesignal from the at least one sensor associated with the electricconductor and based on a second condition relating to the electricconductor.

US Patent Application Publication No. 20190317143 to Gangadhar et al.relates to detecting a broken conductor in a power transmission line. Inan embodiment, a processor receives a signal indicating current on thetransmission line. The processor determines that a broken conductor ispresent on the transmission line based at least in part on a magnitudeof the current being less than a line charging current of thetransmission line and a phase angle of the current leading a respectivephase voltage of the transmission line. The processor effects a controloperation based on the determined broken conductor.

US Patent Application Publication No. 20190324074 to Thompson et al.pertains to detection of a broken conductor in an electric power system.In one embodiment, a broken conductor detector may be configured to bemounted to an electrical conductor and may comprise a communicationsubsystem configured to transmit a signal configured to indicate thatthe conductor is broken. A sensor may determine an operating vector. Aprocessing subsystem may be configured to receive the operating vectorfrom the sensor and to identify when the operating vector is outside ofa range defined by a rest vector and a threshold value. In certainembodiments, the threshold may comprise a three-dimensional sphere. Theprocessing subsystem may determine that the conductor is broken based onthe operating vector remaining outside of the range for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is broken.

US Patent Application Publication No. 20210048486 to Bell et al.describes systems for determining a broken conductor condition in amultiple-phase electric power delivery system. It has been observed thatbroken conductors pose a safety concern when occurring in the presenceof people or vulnerable environmental conditions. Broken conductorconditions disclosed herein may be used to detect and trip the phasewith the broken conductor, thus reducing or even eliminating the safetyrisk. Further, a distance to the opening may be determined.

US Patent Application Publication No. 20210091559 to Mobley et al.pertains to detection of a broken conductor in an electric power system.In one embodiment, a broken conductor detector may be configured to bemounted to an electrical conductor and may comprise a communicationsubsystem configured to transmit a signal configured to indicate thatthe conductor is broken. A sensor may determine a plurality of vectors.A processing subsystem may be configured to receive the plurality ofvectors from the sensor and to identify when the vector is outside of arange defined by a threshold value. The processing subsystem maydetermine that the conductor is falling based on the plurality ofvectors remaining outside of the threshold for a period of timedetermined by the timer subsystem. A signal may be transmitted by thecommunication subsystem to indicate that the conductor is falling.

US Patent Application Publication No. 20210265834 to Wade et al.describes how systems and methods may mitigate risk of fire caused by anelectric power system. In one embodiment, a system may include anintelligent electronic device (IED). The IED includes a communicationsubsystem to receive a signal from a sensor related to a condition ofthe electric conductor. A processing subsystem in communication with thecommunication subsystem may operate in at least two modes comprising ahigh security mode and a fire prevention mode. In the fire preventionmode, the IED may interrupt a flow of electric current based on thesignal from the at least one sensor associated with the electricconductor. In the high security mode, the system may interrupt a flow ofelectric current based on the signal from the at least one sensorassociated with the electric conductor and based on a second conditionrelating to the electric conductor.

Published article 2016 IEEE “Catching Falling Conductors inMidair—Detecting and Tripping Broken Distribution Circuit Conductors atProtection Speeds” by William O'Brien, Eric Udren, Kamal Garg, DennisHaes, and Bala Sridharan describes how when an overhead electric powerdistribution circuit conductor breaks—for example, when a car strikes apole or a splice or clamp fails—the energized conductor falls to ground.The resulting high-impedance ground fault may be difficult or impossibleto detect by relays located in the substation. In any case, no groundfault protection relay can operate until well after the time the faulthas occurred—after the falling energized conductor has hit the groundand created a hazardous situation. For decades, utilities and equipmentmanufacturers have worked to develop methods for tripping thesehazardous ground faults as quickly as possible. This paper describes anew falling conductor detection scheme that trips the affected circuitsection in the narrow time window between the moment of the break andthe time the conductor hits the ground. The affected circuit section isde-energized while the conductor is still falling, eliminating the riskof an arcing ground fault or energized circuits on the ground.

Published article 2019 Schweitzer Engineering Laboratories, Inc.“Detecting and Locating Broken Conductor Faults on High-Voltage Lines toPrevent Autoreclosing Onto Permanent Faults” by Kanchanrao Dase, SajalHarmukh, and Arunabha Chatterjee describes how broken-conductordetection is challenging because the conductor may remain suspendedwithout causing any fault current. Even if the conductor falls to theground, the fault current might remain low, depending on the faultresistance. For low-resistance faults, a relay can detect faults andtrip the line breakers. However, because the relay cannot determinewhether the fault is permanent, it may attempt to reclose, causingfurther stress to the power system. This paper describes a new algorithmthat uses only single-ended measurements to reliably detect brokenconductors and estimate their location by using the charging current ofthe line. The phase angle of this current leads the voltage by aboutL90°, and the magnitude is a function of line length. This method issuitable for power lines that have measurable charging current, and itdetects broken conductors successfully if the relay can measure thecharging current while the conductor is falling in midair.Broken-conductor detection can be used to trip the breakers before theconductor touches the ground and creates a shunt fault. Thus, thealgorithm can prevent such faults and block any attempt to reclose theline. Detecting broken conductors and their location informationprovided by the algorithm can help in quickly resolving broken-conductorfaults. This paper presents three field events from 57.1 kV and 220 kVlines and results from Electromagnetic Transients Program (EMTP)simulations that validate the algorithm.

Notwithstanding the prior art, the present invention is neither taughtnor rendered obvious thereby.

SUMMARY OF THE INVENTION

The present invention involves an enhanced manner in which to monitorthree-phase electric transmission line systems by measuring specifichigh sensitivity parameters with high sensitivity relays that areinstalled in parallel with existing low sensitivity relays. Thus, thepresent invention is a system for preventing ground fault or other shortcircuit in a three-phase electric transmission line system having atleast three lines, caused by a break in a line, which utilizes at leastdual high sensitivity monitoring, which includes: A. a three-phaseelectric transmission system having at least three lines and a pluralityof circuit breakers; B. a plurality of first relay devices connected tosaid transmission system, said plurality of first relay devices having abest sensitivity for measuring line differential overcurrent of above0.1 amps, and thereby being low sensitivity relay devices; C. aplurality of second relay devices connected to said transmission system,said plurality of second relay devices having a best sensitivity formeasuring line differential overcurrent of at least 0.1 amps or loweramps, preferably 0.01 amps or lower amps, and thereby being highsensitivity relay devices, wherein said plurality of second relaydevices are positioned in parallel to said first set of rely devices onsaid transmission system; D. a programmable relay protection systemfunctionally connected to said three-phase electric transmission system,including functionally connected to said plurality of second relaydevices on each line of said electric transmission line system; and E. acommunications system for communications between said second relaydevices and said circuit breakers such that when said relay protectionsystem senses an open conductor broken line when said at least twooperating conditions fall outside of said preset parameter ranges,communicating to open the circuit breaker on said broken line, therebyshutting down power to said broken line before it otherwise causes aground fault or other short circuit, within 1.0 second of sensing saidopen conductor broken line.

The present invention protection system is programmed to include:

-   -   a) presetting parameter ranges of at least two high sensitivity        electric operating conditions, said preset ranges being        acceptable operating parameter ranges, one of said operating        conditions being instantaneous undercurrent, and one other of        said operating conditions being selected from the group        consisting of    -   A) line differential overcurrent; B) negative sequence        overcurrent and C) combinations thereof;    -   b) monitoring means to monitor each line at each of said        plurality of second relay devices for said at least two        operating conditions;    -   c) permitting closed circuit operation when all of said lines        show said at least two operating conditions are within said        preset acceptable operating parameter ranges;    -   d) sensing open conductor broken line changes and tripping a        circuit breaker on a broken line when that line shows said at        least two operating conditions are outside said preset parameter        ranges;    -   e) and completing the sensing and tripping within 1.0 second.

In some embodiments of the present invention system for preventingground fault or other short circuit in a three-phase electrictransmission line system, the plurality of second relay devices on eachline is programmed to monitor both upstream and downstream from each ofsaid plurality of second relay devices such that when a line is broken,the monitored operating conditions of both ends of the break are sensedand reported in the system to effect said shutting down power to saidbroken line by tripping two circuit breakers, one being upstream fromthe break and the other being downstream from the break. Preferably, thesensing and reporting and tripping of two circuit breakers is completedwithin 1.0 second.

In some embodiments of the present invention system, the programmablerelay protection system plurality of second relay devices are programmedto monitor line instantaneous undercurrent, and to monitor sensitiveline differential overcurrent to detect current imbalance online-charging capacitive current. In some embodiments of the presentinvention system, the shutting down the power to said broken line isdelayed by a preset time within the range of about 0.3 seconds to about1 second to protect against a false shut down.

In some embodiments of the present invention system, the programmablerelay protection system plurality of second relay devices are programmedto monitor line instantaneous undercurrent, and to monitor negativesequence overcurrent. In some of these embodiments of the presentinvention system, the shutting down the power to said broken line isdelayed by a preset time within the range of about 0.3 seconds to about1 second to protect against a false shut down.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure differential overcurrent in the range of 0.01 to 0.1amp.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure negative sequence overcurrent in the range of 0.01to 1 amp.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure instantaneous undercurrent in the range of 0.01 to 1amp.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure differential overcurrent in the range of 0.01 to 0.5amp, and so as to monitor and measure instantaneous undercurrent in therange of 0.1 to 1 amp.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure differential overcurrent in the range of 0.01 to 0.1amp.

In some embodiments of the present invention system, the plurality ofsecond relay devices are programmed to be highly sensitive so as tomonitor and measure negative sequence overcurrent in the range of 0.01to 1 amp.

In some embodiments of the present invention system, the relayprotection system includes sufficient software and hardware forrecognizing breakage capacitive current within 10 milliseconds when saidat least one operating condition falls outside of said preset parameterranges, and communicating to open the circuit breaker on said brokenline within 10 milliseconds, thereby shutting down power to said brokenline before it otherwise causes a ground fault or other short circuit.

In some embodiments of the present invention system, the relayprotection system includes a plurality of second relay devices havingphasors for monitoring all three phase voltages and currents and phaseangle similarities and differences to detect capacitive current anddeviations from preset ranges thereof.

In some embodiments of the present invention system, there are at leasttwo AND gates and at least one OR gate for processing monitored datareadings and tripping breakers, including a first AND gate that receivesline differential overcurrent readings and instantaneous undercurrentreadings, and includes a second AND gate that receives negative sequenceovercurrent readings and second instantaneous undercurrent readings.

In some embodiments of the present invention system, there are at leasttwo AND gates and at least one OR gate for processing monitored datareadings and tripping breakers, including a first AND gate that receivesline differential overcurrent readings and instantaneous undercurrentreadings, and includes a second AND gate that receives negative sequenceovercurrent readings and second instantaneous undercurrent readings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate preferred embodiments of theinvention and together with the detail description serve to explain theprinciples of the invention. In the drawings:

FIG. 1 is a block diagram showing some of the features of a Prior Arthigh voltage electric transmission relay protection system having lowsensitivity relays;

FIG. 2 is a block diagram showing some of the features of a PresentInvention high voltage electric transmission relay protection systemthat includes low sensitivity relays with in-parallel high sensitivityrelays. The high sensitivity relays use micro monitoring of highlysensitive line conditions—namely, one of which is instantaneousundercurrent, and the other of which is selected from (i) linedifferential overcurrent, (ii) negative sequence overcurrent, and (iii)combinations thereof, utilizing highly sensitive relays that arein-parallel with the low sensitivity relays;

FIG. 3 illustrates a diagram of a present invention protection systemusing two low sensitivity relays and two high sensitivity programmablerelays located at opposing substations and monitoring at least two ofthe aforesaid conditions on all three lines (also referred to as wires,wire conductors, conductor wires or conductors herein) at bothsubstations on the high sensitivity relays;

FIGS. 4A and 5 show high voltage transmission lines before a break andafter a break (before shorting), respectively, with present inventionrelays (PIRs) in parallel with low sensitivity relays at eachsubstation, and FIG. 4B shows a blown up detailed segment of a portionof FIG. 4A;

FIGS. 6, 7 and 8 show various present invention AND gate/OR gatearrangements programmed into the high sensitivity relays used to monitorconditions and initiate breaker tripping to prevent ground faults aftera line break and before a line touches a tower, pole or ground;

FIG. 9 shows another alternative present invention system gatearrangement for the high sensitivity relays;

FIGS. 10 and 11 , respectively, illustrate examples of Prior Artprotection systems and Present Invention protection systems analysis foran actual 500 kilovolt, 1500 amp high voltage transmission line, and thephenomenal ability of the present invention system to completelyeliminate collateral and catastrophic damage that is possible to occurwith the Prior Art systems;

FIGS. 12 and 13 , respectively, illustrate examples of Prior Artprotection systems and Present Invention protection systems analysis foran actual 115 kilovolt, 100 amp high voltage transmission line, and thephenomenal ability of the present invention system to completelyeliminate collateral and catastrophic damage that is possible to occurwith the Prior Art systems.

DETAILED DESCRIPTION OF THE INVENTION

Electricity begins with production of power, i.e. the source, in theform of any electric-producing-facility, fossil fuel power plant,hydroelectric, wind farm, solar form, hybrid, co-generation, etc. Whenelectricity is produced, it is next distributed and then consumed. Thefour major aspects are production, transmission, distribution andconsumption. Transmission usually begins with high voltage (sometimescalled high tension) lines transmitting from the source, through thelines, to the load. Distribution involves step-down substations withtransformers and other components to regulate electric flow. It is wellknown that resistance will cause huge drops in delivered electricity tothe load, and it is well known that the negative effect of resistancealong the lines (wires) can be significantly reduced by lowering thecurrent and increasing the voltage. As an example, a 110 volt line couldlose over 70% of its value before reaching a load, depending upon linematerial and distance, whereas high voltage lines operating at very highvoltages, such as 345 kilovolts, might lose only 0.5% of its value tothe load over many miles. Large amounts of power can only be transmittedover long distances by very high and extremely high voltage transmissionlines from a practical standpoint, otherwise resistive losses of energyare prohibitive.

For decades (at least 50 years), high voltage transmission systems havegrown into significant sizes that are interconnected into what is calleda grid, e.g. the North America grid. The grid is a mixture of differenttransmission voltages that is utilized because it is often used to shareproduction resources in one region, taking power from one region andsending it to another region. One significant disadvantage is that adowned line or lines, on one segment or region of a grid, may causeother operating segments or regions to overload and shut down. Hence,the domino theory (one falls down and others follow sequentially) hasapplied to grids around the world, causing hundreds of thousands or evenmillions of consumers to lose power for significant periods of time. Tocountermand these happenstances, grid reconfigurations, new equipment,new software, added redundancies and other support features have beenadded to the grid. In addition, line monitoring for short circuits,including ground faults, and shutting down circuits in response, is anintegral part of high voltage (“HV”) transmission systems. For thesereasons, programmable relays have been used to identify and respond toshort circuits, for decades

The term “ground fault” as used herein, is meant to reference adisruption caused by a live wire or other live electric componentunintentionally contacting a conductor, such as a conductive structure,the ground, a body of water, etc. The term “broken line” as used hereinshall be taken broadly to include live wires, live connectors, livesplices and splice components that have experienced a break in thecircuitry with a short or fault that has or is about to occur.

Referring now in detail to the drawings wherein like reference numeralsdesignate corresponding parts throughout the several views, variousembodiments of the present invention system are shown.

The standard in the industry is to monitor the transmission system torecognize a ground fault and to react to it using aforementioned lowsensitivity relays. The conventional steps of the PRIOR ART are shown inFIG. 1 , block 1 (Prior Art High Voltage Electric Transmission RelayProtection System) are:

-   -   (1) deploy programmable, communicating low sensitivity (LS)        relays along transmission lines, block 3;    -   (2) program these LS relays to monitor macro changes in electric        conditions along the lines to identify when a ground fault has        occurred, block 5;    -   (3) communicate to the appropriate breaker to shut down the        breaker after the ground fault has occurred with possible        collateral damage and possible catastrophic damage, block 7;    -   (4) shift power as quickly as possible to by-pass (isolate) the        broken line to other transmission lines to minimize disruption,        block 9 (this occurs with existing equipment and grid        configurations as the transmission system reconfigures);    -   (5) locate the broken line and repair/replace it, block 11, and;    -   (6) restore power to the previously broken line, block 13.

This prior art procedure seems to be used frequently, if notuniversally, but has the disadvantage of collateral damage, ranging fromminor property, livestock or flora and fauna damage, to significantcollateral damage-fires, destruction and the like, to catastrophiccollateral damage-loss life or many lives, destruction of valuableproperty, such as in the millions or even hundreds of millions ofdollars, and even destruction of entire communities. The parametersrelied upon in these prior art systems are affected after a faultoccurs, i.e., when it is too late to prevent collateral ground damage.

The present invention is directed to the elimination of all collateraland catastrophic damage caused by a short or ground fault in existingsystems that presently use low sensitivity relays. This is achieved byutilizing micro monitoring programming in the high sensitivity relays tonot look at ground faults, but to micro monitor small changes incapacitive current and capacitive voltage that occurs after a line isbroken and before it shorts or grounds (that is, before it touches atower, pole, ground or other grounding object). “Micro” as used hereindoes not mean one millionth or other exact measurement, but rather isintended to connote very small measurements on a relative basis, suchmeasurements involving characteristics for which flows are below 0,1amps, and more specifically, those parameters set forth above and below.In this context, the present invention measurements are typically atleast an order of magnitude smaller than present commercial relaysmeasurements that occur upon a short or ground fault. For lower rangehigh voltage systems, the present invention methods are monitoringconditions that are two or even three orders of magnitude smaller.Further, in the present invention methods, timing is critical and theconditions measured are different and critical. This unique approachenables breakers to be shut down (and hence cease electric flow) beforeany collateral damage could otherwise occur.

FIG. 2 shows the steps in the present invention ground fault preventionsystem with its high voltage transmission relay protection system, block21, and preferred embodiments include these steps:

-   -   (1) deploy programmable, communicating high sensitivity relays        along transmission lines in parallel with existing low        sensitivity relays, preferably at or near the substations, block        23. Communications must be very rapid, such as radio, and        preferably optical fiber communications;    -   (2) program these high sensitivity relays to monitor micro        changes in electric conditions, namely:    -   instantaneous undercurrent, and one other of the aforesaid        operating conditions, namely, selected from the group consisting        of a) line differential overcurrent; b) negative sequence        overcurrent and c) combinations thereof, along the lines to        identify when a line break has occurred and to do so before the        broken line creates a fault, block 25, (before it touches a        tower, pole or ground), e.g., within a half-second and        preferably within a few milliseconds;    -   (3) rapidly communicate to the appropriate breakers to shut down        the breakers at both ends of the break before the ground fault        has occurred, block 27 (again within a half-second and        preferably within a few milliseconds) to avoid collateral damage        or catastrophe, had the ground fault actually occurred;    -   (4) shift or by-pass (isolate) power as quickly as possible to        minimize disruption, block 29 (this occurs with existing        equipment and grid configurations as the transmission system        reconfigures);    -   (5) locate the broken line and repair/replace it, block 31, and;    -   (6) restore power to the previously broken line, block 33. Thus,        the present invention system includes the three-line        transmission subsystem, the communicating relay protection        subsystem and the communications subsystem.

By the present methods and devices, it can now be seen that the speed inwhich the monitoring and corrective action takes place is a fraction ofa second or a second. Due to the present invention methods, shut downoccurs before a fault occurs, no damage results, and easier, safer andquicker broken line repair is achieved.

FIG. 3 illustrates a diagram of a present invention ground faultprevention system using two programmable relays, one high sensitivityrelay that is arranged in parallel with existing low sensitivity (LS)relay, located at opposing substations, with the high sensitivity relaymonitoring at least two selected conditions that are not monitored byconventional low sensitivity relays. In one embodiment, these conditionsare: a) instantaneous undercurrent, and b) line differentialovercurrent. In another embodiment, these conditions are: a)instantaneous undercurrent, and b) negative sequence overcurrent. Inanother embodiment, these conditions are: a) instantaneous undercurrent,in combination with b) line differential overcurrent, as well as c)instantaneous undercurrent, in combination with d) negative sequenceovercurrent. Another embodiment is a) instantaneous undercurrent, incombination with b) line differential overcurrent, as well as c)negative sequence overcurrent. Additional, conditions could be added,such as may be described below in conjunction with the gates.

One of the relays is shown in greater detail than the other, but bothare similar except that the present invention high sensitivity relayshave greater sensitivity in its internal structure (more sensitive chipreaders and/or other components, such as higher resolution transformersor chip equivalents) and also, are set to monitor functions not beingmonitored in conventional low sensitivity relays, namely, theinstantaneous undercurrent in combination s set forth in the paragraphimmediately above. In FIG. 3 , a structurally conventional relay device50 is shown with a present-day relay microprocessor with computersoftware, hardware, and firmware that processes the software foradjusting the input parameters of the electric conditions, voltages andcurrents, to determine when adverse conditions occur. A second, almostidentical but high sensitivity, relay 94 is also shown. These two relays50 and 94 are programmed differently from normal relays used in theindustry, as they are programmed to measure sensitive readings and notlarge readings, and, more specifically, are programmed tomeasure/monitor changes that occur before fault occurs. These “micro”changes relate to what occurs at the broken ends of a line before eitherend touches anything to short or ground. Such readings are bypassed, orignored, by the prior art systems programming, as breakers are nottripped in the prior art systems until after the short or fault occurs.Here the aforementioned conditions are monitored and when they deviatefrom the preset acceptable operating ranges, the breakers are tripped.These relays send trip signals to the circuit breaker(s) within asecond, and even within 20 or so milliseconds to de-energize the line.In preferred embodiments, the present invention relays are programmed tomonitor in both directions (upstream and downstream from current flow)and trip both related breakers.

Table I lists the various components of the present invention protectionsystem shown in FIG. 3 , and the detailed relationship of each componentis set forth below Table I:

TABLE 1 FIG. 3 Present Invention System Components (Drawing ReferenceNumber and Component)  50 Present Invention First Relay.  51 Three PhasePower Grid.  52 A phase transmission line conductor.  54 B phasetransmission line conductor.  56 C phase transmission line conductor. 58 A phase potential transformer.  60 B phase potential transformer. 62 C phase potential transformer.  64 A phase current transformer.  66B phase current transformer.  68 C phase current transformer.  70 Wireconnecting 58 to relay 50 for A phase voltage input. (VA)  72 Wireconnecting 60 to relay 50 for B phase voltage input. (VB)  74 Wireconnecting 60 to relay 50 for C phase voltage input. (VC)  76 Wireconnecting 64 to relay 50 for A phase current input. (IA)  78 Wireconnecting 66 to relay 50 for B phase current input. (IB)  80 Wireconnecting 68 to relay 50 for C phase current input. (IC)  82 Wireconnecting ground to relay 50 for ground potential for use in relay 50.(GND)  84 Wire connecting the trip signal from Relay 50 to CircuitBreaker 86.  86 Circuit Breaker associated with the downed conductordetection system connected to Relay 50.  88 Circuit Breaker associatedwith the transmission line at the other end of the line, associated withthe downed conductor detection system connected to Relay 94.  90Communications port to send and receive data communications.  92Communications port for testing Relay 50 and for making software changesand modifying relay settings.  94 Present Invention Second Relay.  96Communication Center between Relays 50 and 94. 100 First Substation. 200Second Substation (next downstream from First Substation.

The transmission lines of power grid 51 transport electric power to bedelivered to meet customer demand. At the power generation end, astep-up transformer substation transmits the power through thetransmission lines at very high voltages, and at the downstream end, astep-down transformer sends power through a distribution line at normalvoltages. In between the beginning and end of a power grid, numerousintermediate substations are positioned to distribute power to localusers. In this FIG. 3 , adjacent (First and Second) substations 100 and200 are shown to be 50 miles apart. Relay 50 monitors the currents inelectric power grid 51 on the specific transmission line associated withthis specific transmission line linked to Relay 50 at First Substation100. The power grid 51 transmission system is a three-phase system totransport power over long distances to safely and economically deliverenergy to meet customer demand. The power grid 51 illustrated in thisFigure is a three-phase alternating current system represented bytransmission line conductors 52, 54, and 56. Relay 50 monitors or sensesthe current and voltage levels in each of the phases of the three-phasesystem. A circuit breaker 86 is provided for disconnecting thetransmission line being protected from the power grid 51 when aconductor (wire) fails for any reason, such as a broken conductor(wire), a failed splice, gunshot damage, failed connectors or othercomponents resulting in an open conductor condition.

Relay 50 receives input voltages from A, B, C phase potentialtransformers 58, 60, and 62 on transmission line conductors 52, 54, and56, and the proportional values are connected to Relay 50 by wires 70,72 and 74 to provide proportional voltage values to Relay 50 connectionsat VA, VB and VC, respectively.

Current levels on the transmission line conductors 52, 54, and 56 areperformed by connecting a current transformer or some type of couplingcapacitor voltage transformer, or other current sensing device to theline conductors 52, 54 and 56 at A, B, C phase current transformers 64,66 and 68. The current flow output of A, B, C phase current transformers64, 66 and 68 are directly proportional to the line currents in lineconductors 52, 54 and 56. These current transformers 64, 66 and 68 arephysically connected or magnetically coupled to each line as shown inthe Figure. The primary windings of transformers 64, 66, and 68 areenergized in accordance with the line currents in line conductors 52,54, and 56, respectively. The secondary windings of the transformers 64,66 and 68 are connected to Relay 50 via lines 76, 78 and 80,respectively at IA, IB and IC. Relay 50 is connected to the circuitbreaker 86 via wire 84 connection at Relay 50 and terminating at theassociated circuit breaker. This is commonly known as output contacts toperform the trip function located in the circuit breaker controlcabinet. Wire 82 connects relay 50 to ground GND, as shown.

There is a second present invention Relay 94 at substation 200 withcircuit breaker 88, that is 50 miles downstream from substation 100.Relay 94 is identical to Relay 50 and therefore its details are notrepeated.

Relay 50 includes a communications port 90, such as a RS-485 serialport, or RS-232 or Fiber Optic connection which is used to transfer datato/from a remote location communications center 96 and as a direct linkbetween Relay 50 at substation 100 of a transmission line, and, Relay 94at the next substation 200 at the other end of the transmission line tocommunicate the status of the line from both ends. Relay 50 alsoincludes a second communications port 92, such as a USB port which isprovided for testing and local programming of Relay 50.

The relays 50 and 94 are coordinated by their programming andcommunications center 96. In these preferred embodiments, at a minimumeach relay would monitor three lines for capacitive potential orcapacitive current to recognize deviations from preset (programmed)acceptable operating ranges. More preferably, they each monitor threelines for a) instantaneous undercurrent, in combination with b) linedifferential overcurrent, and/or c) instantaneous undercurrent, incombination with d) negative sequence overcurrent, to recognizedeviations from preset (programmed) acceptable operating ranges. In somepreferred embodiments, the current magnitudes and phase angles arecompared. Degree of phase synchronization may be determinative orcontribute to the analysis to determine whether a significant enoughdeviation has occurred to trigger tripping breakers.

FIGS. 4A and 5 show high voltage transmission lines before a break andafter a break (before shorting), respectively, with existing lowsensitivity relays (ERs) in parallel with present invention relays(PIRs) at each substation. FIG. 4B represents a blow up of a portion ofFIG. 4A, particularly clearly showing the in-parallel arrangement of thehigh sensitivity relays with the low sensitivity relays. All threeFigures are taken together in this discussion and identical componentsare identically numbered. A power generating station 201 generates threephase electricity transmitted by lines 203, 205 and 207 to step-upsubstation 209. Substation 209 has an existing relay ER 220, and animproved high sensitivity present invention relay PIR 241 that functionsin like fashion to relay 50 of FIG. 3 . The power is transmitted at highvoltage over the three phase lines from tower 211 to subsequent towers213, 219, 221, 223 and 225. There are large industrial consumers thatdraw from these lines such as factories 215 and 239. There aresubstations along the way, including substations 217, 227 and 237 andeach has an existing relay ER 230, 240 and 250 and a Present InventionRelay PIR 243, 245 and 247 respectively, such as described above inconjunction with relay 50 of FIG. 3 . The substations are step-downsubstations (with a step-down transformer to reduce voltage) thatdistribute power to users via conventional poles 231 and 233 to userssuch as school 229 and residence 235.

FIG. 4B shows one portion of FIGS. 4A and 5 , at substation 209, andspecifically showing the main three phase lines 203, 205 and 207 passingthrough existing low sensitivity relay 220. The new high sensitivityrelay 241 is not in series but rather in parallel with relay 220connected by three phase parallel take-off lines 210, 212 and 214. Allof the pairs of PIRs and ERs of FIG. 4A and FIG. 5 are arranged in thisfashion. The PIRs are programmed as high sensitivity relays to monitormicro changes in electric conditions, namely: instantaneousundercurrent, and one other of the aforesaid operating conditions,namely, selected from the group consisting of a) line differentialovercurrent; b) negative sequence overcurrent and c) combinationsthereof, along the lines to identify when a line break has occurred andto do so before the broken line creates a fault (before it touches atower, pole or ground), e.g., within a half-second and preferably withina few milliseconds. The ERs are not capable of these measurements,reactions, etc. because they have neither adequate sensitivity, norconcomitant programming.

Because the PIRs monitor upstream and downstream, when a line breaks (asshown in FIG. 5 between towers 219 and 221) the nearest upstream anddownstream PIRs (243 and 245) monitoring the aforesaid conditions, willsee deviant conditions generated from both ends of the break, and willdirect a breaker tripping associated with those two substations (217 and227) for the broken line before the broken line segments (ends) touch atower or ground or other short. This happens in less than 25milliseconds and completely prevents any short or ground from occurringand eliminates any collateral damage or worse-catastrophic damage toperson, structure, animal, flora and fauna.

FIGS. 6, 7, 8 and 9 show various present invention AND gate/OR gatearrangements of the present invention systems, used to monitorconditions and initiate breaker tripping to prevent ground faults aftera line break and before a line touches a tower, pole or ground.Identical components shown in each of these Figures are identicallynumbered.

In FIG. 6 gate diagram, the preferred AND gate 307 and AND gate 309 areused to require a tripping signal directive 303 through OR gate 305. AtAND gate 307, simultaneous deviations from preset ranges for linedifferential, block 315 and for undercurrent, block 317, are necessaryfor an action signal to pass through the gate. At AND gate 309,simultaneous deviations from preset ranges for directional overcurrentT-1, block 319 and for directional current T-2 317, block 321, arenecessary for an action signal to pass through the gate. Once an actionsignal passes through one AND gate or the other AND gate, OR gate 305sends the trip output directive 303 to trip the breakers.

In FIG. 7 , components shown in FIG. 6 are identically numbered here,except that there is a different AND gate 313. This gate 313 illustratesa preferred embodiment of the present invention. Here at AND gate 313,simultaneous deviations from preset ranges for a negative sequence,block 327, and an undercurrent, block 329, are both required for anaction signal to pass through AND gate 313.

In FIG. 8 , all that is shown in FIG. 6 is repeated and works the sameway as in FIG. 6 , except that there is a third AND gate 313. Here atAND gate 313, simultaneous deviations from preset ranges for a negativesequence (voltage or current, preferably current), block 327, and anundercurrent, block 329, are both required for an action signal to passthrough AND gate 313.

In FIG. 9 , all that is shown in FIG. 6 is repeated and works the sameway as in FIG. 6 , except that there are now four AND gates, namely, ANDgates 307, 309, 311 and 313 each functioning as set forth above in FIGS.6, 7 and 8 .

While these gates assure reliability of the system by buildingredundancy into it, other variations for gate requirements within thevarious conditions monitored in the present invention may bealternatively be used without exceeding the scope of the presentinvention.

EXAMPLES 1 AND 2—PRIOR ART vs PRESENT INVENTION PROTECTION SYSTEMS—500KILOVOLTS TRANSMISSION SYSTEM

FIGS. 10 and 11 , respectively, illustrate Prior Art protection systemsand Present Invention protection systems analysis for an actual 500kilovolt, 1500 amp high voltage transmission line, and the significantability of the present invention system to completely eliminatecollateral and catastrophic damage that is possible or even likely tooccur with the Prior Art systems.

In FIG. 10 , Example 1, the prior art system of shutting down powerafter a fault is identified, is shown in graphic format as current vs.time. (Note that as to all FIGS. 10 through 13 , the horizontal timesegments and the vertical voltage segments are not intended to beproportional, only illustrative. The values in amps are accurate basedon real conditions and calculations.) During t-1, the system is runningwith no breaks and hence has a normal average current of 1650 amps. Attime t-2, a line breaks and current drops to approximately 100 amps.This when the broken line is falling but has not yet hit or touched aground or short object, such as a tower or other structure or earth.This amperage stays at 100 until ground occurs at t-3, and then thecurrent leaps to 3514 amps. This is enough to cause fires, destroybuildings and kill people, fauna and flora. (It is understood that anycurrent/amperage hitting the ground could initiate a fire that couldconsequentially cause such damage.) At t-4, the breaker is tripped andcurrent drops to 0, but it is too late as damage such as wildfires, hasalready occurred.

In FIG. 11 , Example 2, the present invention system of shutting downpower before a fault occurs, is shown in graphic format as current vs.time. During t-1, the system is running with no breaks and hence has anormal average current of 1650 amps. At time t-2, a line breaks andcurrent drops to approximately 100 amps. This when the broken line isfalling but has not yet hit or touched a ground or short object, such asa tower or other structure or earth. This amperage stays at 100 untilthe present invention recognizes micro condition changes and trips thebreakers, typically within 20 to 30 milliseconds, and thus, no groundoccurs at t-3. The current remains at 0 amps. Because no fault or shortoccurs, all possibility to cause fires, destroy buildings and killpeople, fauna and flora, are mitigated or eliminated. At t-4, thebreaker has already been tripped and current remains at 0, until repairand restoration are completed, and then, the transmission is back tonormal.

EXAMPLES 3 AND 4—PRIOR ART vs PRESENT INVENTION PROTECTION SYSTEMS—115KILOVOLTS TRANSMISSION SYSTEM

FIGS. 12 and 13 , respectively, illustrate Prior Art protection systemsand Present Invention protection systems analysis for an actual 115kilovolt, 100 amp high voltage transmission line, and the phenomenalability of the present invention system to completely eliminatecollateral and catastrophic damage that is possible to occur with thePrior Art systems. In these examples, FIGS. 12 and 13 are compared: Attime t-1, the system is running normal and the current is 503 amps, whenat time t-2, a line break occurs, the current in the broken line dropsto about 0.8 amps. This when the broken line is falling but has not yethit or touched a ground or short object, such as a tower or otherstructure or earth. This amperage stays at 0.8 and in the prior artExample 3, FIG. 12 , when the short or fault occurs, the current jumpsto 7000 amps with potentially catastrophic consequences. In the presentinvention Example 4, still in the time frame of t-2, the presentinvention recognizes micro condition changes and trips the breakers,typically within 20 to 30 milliseconds, and thus, no ground occurs att-3. The current remains at 0 amps. Because no fault or short occurs,all possibility to cause fires, destroy buildings and kill people, faunaand flora, are mitigated or eliminated. At t-4, the breaker has alreadybeen tripped and current remains at 0, until repair and restoration arecompleted, and then, the transmission is back to normal.

To further confirm the efficacy of the present invention, an independentconsulting firm performed simulation testing at its test facilities. Theconsulting firm is a leading test facility for RTDS (Real Time DigitalSimulator) and they test various dynamic simulations for leadingutilities and national labs throughout the country. The tests were doneon an actual model of a California power company's electric transmissionsystem on voltages ranging from 500 k to 70 kV. The test results furtherdemonstrated that the present invention technology described hereincorrectly tripped for open conductors in small fractions of a second andhad not tripped unnecessarily for through fault conditions and low loadconditions. Every correctly tripped open conductor was fast enough toshut down the system before ground faults (and concomitant collateraldamage) could occur.

Although particular embodiments of the invention have been described indetail herein with reference to the accompanying drawings, it is to beunderstood that the invention is not limited to those particularembodiments, and that various changes and modifications may be affectedtherein by one skilled in the art without departing from the scope orspirit of the invention as defined in the appended claims. For example,the shapes of the various components herein may be changed; specificrelays may be modified or enhanced; communications may be by radio orfiber optics or by any rapid communication system that is or becomesavailable.

1-20. (Cancelled).
 21. A system for preventing ground fault or othershort circuit in a three-phase electric transmission line system havingat least three lines, caused by a break in a line, which utilizes atleast dual high sensitivity monitoring, which comprises: A. athree-phase electric transmission system having at least three lines anda plurality of circuit breakers; B. a plurality of first relay devicesconnected to said transmission system, said plurality of first relaydevices having a best sensitivity for measuring line differentialovercurrent of above 0.1 amps, and thereby being low sensitivity relaydevices; C. a plurality of second relay devices connected to saidtransmission system, said plurality of second relay devices having abest sensitivity for measuring line differential overcurrent of at least0.01 amps or lower amps, and thereby being high sensitivity relaydevices, wherein said plurality of second relay devices are positionedin parallel to said first set of rely devices on said transmissionsystem; D. a programmable relay protection system functionally connectedto said three-phase electric transmission system, including functionallyconnected to said plurality of second relay devices on each line of saidelectric transmission line system, said relay protection system beingprogrammed to include: a) preset parameter ranges of at least two highsensitivity electric operating conditions, said preset ranges beingacceptable operating parameter ranges, one of said operating conditionsbeing instantaneous undercurrent, and one other of said operatingconditions being selected from the group consisting of a) linedifferential overcurrent; b) negative sequence overcurrent and c)combinations thereof, wherein said plurality of second relay devices areprogrammed to be highly sensitive so as to monitor and measureinstantaneous undercurrent in the range of 0.01 to 1 amps, and whereinsaid plurality of second relay devices are programmed to be highlysensitive so as to monitor and measure one other of said operatingconditions selected from the group consisting of a) line differentialovercurrent; b) negative sequence overcurrent and c) combinationsthereof, in the range of 0.01 to 0.1 amps, and; b) monitoring means tomonitor each line at each of said plurality of second relay devices forsaid at least two operating conditions; c) permitting closed circuitoperation when all of said lines show said at least two operatingconditions are within said preset acceptable operating parameter ranges;d) sensing open conductor broken line changes and tripping a circuitbreaker on a broken line when that line shows said at least twooperating conditions are outside said preset parameter ranges; e) andcompleting the sensing and tripping within 1.0 second; E. acommunications system for communications between said second relaydevices and said circuit breakers such that when said relay protectionsystem senses an open conductor broken line when said at least twooperating conditions fall outside of said preset parameter ranges,communicating to open the circuit breaker on said broken line, therebyshutting down power to said broken line before it otherwise causes aground fault or other short circuit, within 1.0 second of sensing saidopen conductor broken line.
 22. The system for preventing ground faultor other short circuit in a three-phase electric transmission linesystem of claim 21 wherein said plurality of second relay devices oneach line is programmed to monitor both upstream and downstream fromeach of said plurality of second relay devices such that when a line isbroken, the monitored operating conditions of both ends of the break aresensed and reported in the system to effect said shutting down power tosaid broken line by tripping two circuit breakers, one being upstreamfrom the break and the other being downstream from the break.
 23. Thesystem of claim 23 wherein said sensing and reporting and tripping oftwo circuit breakers is completed within 1.0 second.
 24. The system forpreventing ground fault or other short circuit in a three-phase electrictransmission line system of claim 21 wherein said programmable relayprotection system plurality of second relay devices are programmed tomonitor line instantaneous undercurrent, and to monitor sensitive linedifferential overcurrent's to detect current imbalance on line-chargingcapacitive current.
 25. The system for preventing ground fault or othershort circuit in a three-phase electric transmission line system ofclaim 23 wherein shutting down the power to said broken line is delayedby a preset time within the range of about 0.3 seconds to about 1 secondto protect against a false shut down.
 26. The system for preventingground fault or other short circuit in a three-phase electrictransmission line system of claim 21 wherein said programmable relayprotection system plurality of second relay devices are programmed tomonitor line instantaneous undercurrent, and to monitor and negativesequence overcurrent.
 27. The system for preventing ground fault orother short circuit in a three-phase electric transmission line systemof claim 23 wherein said programmable relay protection system pluralityof second relay devices are programmed to monitor line instantaneousundercurrent, and to monitor and negative sequence overcurrent.
 28. Thesystem for preventing ground fault or other short circuit in athree-phase electric transmission line system of claim 26 whereinshutting down the power to said broken line is delayed by a preset timewithin the range of about 0.3 seconds to about 1 second to protectagainst a false shut down.
 29. The system for preventing ground fault orother short circuit in a three-phase electric transmission line systemof claim 21 wherein said plurality of second relay devices areprogrammed to be highly sensitive so as to monitor and measuredifferential overcurrent in the range of 0.01 to 0.5 amp, and so as tomonitor and measure instantaneous undercurrent in the range of 0.1 to 1amp.
 30. The system for preventing ground fault or other short circuitin a three-phase electric transmission line system of claim 23 whereinsaid plurality of second relay devices are programmed to be highlysensitive so as to monitor and measure differential overcurrent in therange of 0.01 to 0.1 amp.
 31. The system for preventing ground fault orother short circuit in a three-phase electric transmission line systemof claim 23 wherein said plurality of second relay devices areprogrammed to be highly sensitive so as to monitor and measure negativesequence overcurrent in the range of 0.01 to 1 amp.
 32. The system forpreventing ground fault or other short circuit in a three-phase electrictransmission line system of claim 23 wherein said plurality of secondrelay devices are programmed to be highly sensitive so as to monitor andmeasure differential overcurrent in the range of 0.01 to 0.5 amp, and soas to monitor and measure instantaneous undercurrent in the range of 0.1to 1 amp.
 33. The system for preventing ground fault or other shortcircuit in a three-phase electric transmission line system of claim 21wherein said relay protection system includes sufficient software andhardware for recognizing breakage capacitive current within 10milliseconds when said at least one operating condition falls outside ofsaid preset parameter ranges, and communicating to open the circuitbreaker on said broken line within 10 milliseconds, thereby shuttingdown power to said broken line before it otherwise causes a ground faultor other short circuit.
 34. The system for preventing ground fault orother short circuit in a three-phase electric transmission line systemof claim 21 wherein said relay protection system includes a plurality ofsecond relay devices having phasors for monitoring all three phasevoltages and currents and phase angle similarities and differences todetect capacitive current and deviations from preset ranges thereof. 35.The system for preventing ground fault or other short circuit in athree-phase electric transmission line system of claim 21 wherein thereare at least two AND gates and at least one OR gate for processingmonitored data readings and tripping breakers, including a first ANDgate that receives line differential overcurrent readings andinstantaneous undercurrent readings, and includes a second AND gate thatreceives negative sequence overcurrent readings and second instantaneousundercurrent readings.
 36. The system for preventing ground fault orother short circuit in a three-phase electric transmission line systemof claim 23 wherein there are at least two AND gates and at least one ORgate for processing monitored data readings and tripping breakers,including a first AND gate that receives line differential overcurrentreadings and instantaneous undercurrent readings, and includes a secondAND gate that receives negative sequence overcurrent readings and secondinstantaneous undercurrent readings.